Predict the falls!

Objective:

  • Develop and validate a prediction model for inpatient falls

Methods:

  • Time-to-event (Cox regression) model with updates throughout admission
  • Routine Electronic Medical Records data only
  • Good model assessment methods
  • Good reporting
  • Predictions through to first 14 days of admission

Data

Variable

Measure

Hospital

All

1

2

3

4

5

Inpatient admissions

Count

462,891

359,075

150,458

124,149

10,983

1,107,556

Days

1,198,736

612,658

256,887

273,179

31,882

2,373,343

Days (truncated at 14 days)

794,398

485,189

197,951

228,770

23,825

1,730,133

Female

Count (%)

191,732 (41%)

205,809 (57%)

89,113 (59%)

65,440 (53%)

7,364 (67%)

559,458 (51%)

Falls (truncated at 14 days)

Count

3,027

1,377

638

828

134

6,004

Fallers

2,678 (0.58%)

1,248 (0.35%)

562 (0.37%)

731 (0.59%)

122 (1.11%)

5,341 (0.48%)

Age

Median (IQR)

63 (48 - 74)

42 (26 - 63)

52 (31 - 72)

61 (43 - 77)

38 (26 - 71)

56 (35 - 72)

Length of stay

Median (IQR)

0.3 (0.1 - 1.3)

0.3 (0.2 - 1.2)

0.3 (0.2 - 1.2)

0.4 (0.2 - 2.1)

1.0 (0.2 - 2.3)

0.3 (0.2 - 1.4)

Medical service

Genmed (count)

22,837

26,694

22,678

22,869

5,042

100,120

Orthopaedics (count)

15,833

10,694

< 100

8,138

< 100

34,665

Psychiatry (count)

16,932

12,209

2,729

< 100

< 100

31,870

Rehabilitation (count)

7,840

905

< 100

8,912

< 100

17,657

Neurosurgery (count)

5,449

< 100

< 100

< 100

< 100

5,449

Palliative medicine (count)

< 100

1,553

613

1,573

< 100

3,739

Geriatrics (count)

2,145

< 100

< 100

< 100

< 100

2,145

Psychogeriatric (count)

628

< 100

< 100

< 100

< 100

628

Spinal (count)

378

< 100

< 100

< 100

< 100

378

Other (count)

390,849

307,020

124,438

82,657

5,941

910,905

Admission source

Emergency department - this hospital (count)

128,782

182,224

77,243

84,570

3,990

476,809

Outpatient department - this hospital (count)

208,239

91,621

38,291

29,378

4,160

371,689

Routine readmission no referral required (count)

84,698

63,475

25,576

7,002

327

181,078

Admitted pt transferred from other hosp (count)

20,187

3,906

1,186

2,084

744

28,107

Private medical practitioner (not Psychiatry) (count)

11,119

136

340

616

< 100

12,221

Residential aged care service (count)

2,140

< 100

< 100

< 100

< 100

2,166

Community service (count)

257

1,237

237

363

< 100

2,130

Other (count)

7,469

16,471

7,582

118

1,716

33,356

Data

Variable

Measure

Hospital

All

1

2

3

4

5

Inpatient admissions

Count

462,891

359,075

150,458

124,149

10,983

1,107,556

Days

1,198,736

612,658

256,887

273,179

31,882

2,373,343

Days (truncated at 14 days)

794,398

485,189

197,951

228,770

23,825

1,730,133

Female

Count (%)

191,732 (41%)

205,809 (57%)

89,113 (59%)

65,440 (53%)

7,364 (67%)

559,458 (51%)

Falls (truncated at 14 days)

Count

3,027

1,377

638

828

134

6,004

Fallers

2,678 (0.58%)

1,248 (0.35%)

562 (0.37%)

731 (0.59%)

122 (1.11%)

5,341 (0.48%)

Age

Median (IQR)

63 (48 - 74)

42 (26 - 63)

52 (31 - 72)

61 (43 - 77)

38 (26 - 71)

56 (35 - 72)

Length of stay

Median (IQR)

0.3 (0.1 - 1.3)

0.3 (0.2 - 1.2)

0.3 (0.2 - 1.2)

0.4 (0.2 - 2.1)

1.0 (0.2 - 2.3)

0.3 (0.2 - 1.4)

Medical service

Genmed (count)

22,837

26,694

22,678

22,869

5,042

100,120

Orthopaedics (count)

15,833

10,694

< 100

8,138

< 100

34,665

Psychiatry (count)

16,932

12,209

2,729

< 100

< 100

31,870

Rehabilitation (count)

7,840

905

< 100

8,912

< 100

17,657

Neurosurgery (count)

5,449

< 100

< 100

< 100

< 100

5,449

Palliative medicine (count)

< 100

1,553

613

1,573

< 100

3,739

Geriatrics (count)

2,145

< 100

< 100

< 100

< 100

2,145

Psychogeriatric (count)

628

< 100

< 100

< 100

< 100

628

Spinal (count)

378

< 100

< 100

< 100

< 100

378

Other (count)

390,849

307,020

124,438

82,657

5,941

910,905

Admission source

Emergency department - this hospital (count)

128,782

182,224

77,243

84,570

3,990

476,809

Outpatient department - this hospital (count)

208,239

91,621

38,291

29,378

4,160

371,689

Routine readmission no referral required (count)

84,698

63,475

25,576

7,002

327

181,078

Admitted pt transferred from other hosp (count)

20,187

3,906

1,186

2,084

744

28,107

Private medical practitioner (not Psychiatry) (count)

11,119

136

340

616

< 100

12,221

Residential aged care service (count)

2,140

< 100

< 100

< 100

< 100

2,166

Community service (count)

257

1,237

237

363

< 100

2,130

Other (count)

7,469

16,471

7,582

118

1,716

33,356

Data

Variable

Measure

Hospital

All

1

2

3

4

5

Inpatient admissions

Count

462,891

359,075

150,458

124,149

10,983

1,107,556

Days

1,198,736

612,658

256,887

273,179

31,882

2,373,343

Days (truncated at 14 days)

794,398

485,189

197,951

228,770

23,825

1,730,133

Female

Count (%)

191,732 (41%)

205,809 (57%)

89,113 (59%)

65,440 (53%)

7,364 (67%)

559,458 (51%)

Falls (truncated at 14 days)

Count

3,027

1,377

638

828

134

6,004

Fallers

2,678 (0.58%)

1,248 (0.35%)

562 (0.37%)

731 (0.59%)

122 (1.11%)

5,341 (0.48%)

Age

Median (IQR)

63 (48 - 74)

42 (26 - 63)

52 (31 - 72)

61 (43 - 77)

38 (26 - 71)

56 (35 - 72)

Length of stay

Median (IQR)

0.3 (0.1 - 1.3)

0.3 (0.2 - 1.2)

0.3 (0.2 - 1.2)

0.4 (0.2 - 2.1)

1.0 (0.2 - 2.3)

0.3 (0.2 - 1.4)

Medical service

Genmed (count)

22,837

26,694

22,678

22,869

5,042

100,120

Orthopaedics (count)

15,833

10,694

< 100

8,138

< 100

34,665

Psychiatry (count)

16,932

12,209

2,729

< 100

< 100

31,870

Rehabilitation (count)

7,840

905

< 100

8,912

< 100

17,657

Neurosurgery (count)

5,449

< 100

< 100

< 100

< 100

5,449

Palliative medicine (count)

< 100

1,553

613

1,573

< 100

3,739

Geriatrics (count)

2,145

< 100

< 100

< 100

< 100

2,145

Psychogeriatric (count)

628

< 100

< 100

< 100

< 100

628

Spinal (count)

378

< 100

< 100

< 100

< 100

378

Other (count)

390,849

307,020

124,438

82,657

5,941

910,905

Admission source

Emergency department - this hospital (count)

128,782

182,224

77,243

84,570

3,990

476,809

Outpatient department - this hospital (count)

208,239

91,621

38,291

29,378

4,160

371,689

Routine readmission no referral required (count)

84,698

63,475

25,576

7,002

327

181,078

Admitted pt transferred from other hosp (count)

20,187

3,906

1,186

2,084

744

28,107

Private medical practitioner (not Psychiatry) (count)

11,119

136

340

616

< 100

12,221

Residential aged care service (count)

2,140

< 100

< 100

< 100

< 100

2,166

Community service (count)

257

1,237

237

363

< 100

2,130

Other (count)

7,469

16,471

7,582

118

1,716

33,356

Data

Variable

Measure

Hospital

All

1

2

3

4

5

Inpatient admissions

Count

462,891

359,075

150,458

124,149

10,983

1,107,556

Days

1,198,736

612,658

256,887

273,179

31,882

2,373,343

Days (truncated at 14 days)

794,398

485,189

197,951

228,770

23,825

1,730,133

Female

Count (%)

191,732 (41%)

205,809 (57%)

89,113 (59%)

65,440 (53%)

7,364 (67%)

559,458 (51%)

Falls (truncated at 14 days)

Count

3,027

1,377

638

828

134

6,004

Fallers

2,678 (0.58%)

1,248 (0.35%)

562 (0.37%)

731 (0.59%)

122 (1.11%)

5,341 (0.48%)

Age

Median (IQR)

63 (48 - 74)

42 (26 - 63)

52 (31 - 72)

61 (43 - 77)

38 (26 - 71)

56 (35 - 72)

Length of stay

Median (IQR)

0.3 (0.1 - 1.3)

0.3 (0.2 - 1.2)

0.3 (0.2 - 1.2)

0.4 (0.2 - 2.1)

1.0 (0.2 - 2.3)

0.3 (0.2 - 1.4)

Medical service

Genmed (count)

22,837

26,694

22,678

22,869

5,042

100,120

Orthopaedics (count)

15,833

10,694

< 100

8,138

< 100

34,665

Psychiatry (count)

16,932

12,209

2,729

< 100

< 100

31,870

Rehabilitation (count)

7,840

905

< 100

8,912

< 100

17,657

Neurosurgery (count)

5,449

< 100

< 100

< 100

< 100

5,449

Palliative medicine (count)

< 100

1,553

613

1,573

< 100

3,739

Geriatrics (count)

2,145

< 100

< 100

< 100

< 100

2,145

Psychogeriatric (count)

628

< 100

< 100

< 100

< 100

628

Spinal (count)

378

< 100

< 100

< 100

< 100

378

Other (count)

390,849

307,020

124,438

82,657

5,941

910,905

Admission source

Emergency department - this hospital (count)

128,782

182,224

77,243

84,570

3,990

476,809

Outpatient department - this hospital (count)

208,239

91,621

38,291

29,378

4,160

371,689

Routine readmission no referral required (count)

84,698

63,475

25,576

7,002

327

181,078

Admitted pt transferred from other hosp (count)

20,187

3,906

1,186

2,084

744

28,107

Private medical practitioner (not Psychiatry) (count)

11,119

136

340

616

< 100

12,221

Residential aged care service (count)

2,140

< 100

< 100

< 100

< 100

2,166

Community service (count)

257

1,237

237

363

< 100

2,130

Other (count)

7,469

16,471

7,582

118

1,716

33,356

Cross-validation

Model*

Inpatient admissions

Patient days (truncated at 14 days)

Falls (n)

Model parameters (n)

Events per parameter

Fold: 1

644,665

935,735

2,977

22

135

Fold: 2

748,481

1,244,944

4,627

26

178

Fold: 3

957,098

1,532,182

5,366

26

206

Fold: 4

983,407

1,501,363

5,176

26

199

Fold: 5

1,096,573

1,706,308

5,870

26

226

Final

1,107,556

1,730,133

6,004

26

231

*Model represents the cross-validation fold models and the final model fit with all patient data. The fold models are those fit during internal-external cross-validation and incorporate all patient data except for the associated hospital of the same number. For example, the 'Fold: 1' model was fit using patient data from hospitals 2 to 5, with hospital 1 being the validation set.

Discrimination

Calibration

Summary

  • Highly discriminant inpatient falls prediction model
  • Calibration not ideal but may be be best suited to assign treatment rather than provide risk estimates
  • First use of time-to-event model in inpatient falls prediction with time-varying covariates
  • One of the largest datasets and first use of internal-external cross-validation